Modified graphene oxide / polyaniline composite material and application thereof in water-based anticorrosive antistatic coating

Abstract

The invention provides a polyaniline / modified graphene oxide composite material and a preparation method thereof. The preparation method comprises the following steps: dispersing purified graphene oxide, performing ultrasonic treatment, heating, adding a modifier for modification, centrifuging, taking precipitate, freezing, drying and grinding to obtain modified graphene oxide powder; mixing the powder with an aniline solution in doped acid to form a modified graphene oxide / aniline acid solution; dissolving ammonium persulfate in the doped acid to prepare an ammonium persulfate acid solution; and slowly dropwise adding the solution into the solution, carrying out in-situ polymerization, and carrying out suction filtration, washing and drying to obtain the composite material. According to the method, through chemical modification and in-situ polymerization processes, the problems that a single filler is poor in dispersity, a conductive network is discontinuous, and anti-corrosion and anti-static performance is difficult to synergistically improve are solved, and the process is simple and convenient and suitable for industrialization.

Description

Technical Field

[0001] The present invention relates to a conductive filler for an anti-corrosion and antistatic coating, belonging to the technical field of functional coating materials. Specifically, it is a polyaniline / modified graphene oxide composite material and its preparation method, as well as its preparation method in a waterborne polyurethane anti-corrosion and antistatic coating. Background Art

[0002] Metal corrosion and static electricity accumulation are important threats to the long-term stable operation of industrial equipment. Especially in the fields of ocean engineering, petrochemical industry, electronic equipment, etc., corrosion and static electricity problems not only lead to equipment failure, but may also trigger safety accidents. Traditional anti-corrosion coatings mostly use solvent-based epoxy resin or polyurethane systems. Although they can provide certain protection effects, their high volatile organic compound (VOC) content causes serious harm to the environment and human health. With the increasingly strict environmental protection regulations, waterborne coatings have gradually become a research hotspot due to their low VOC emissions, non-toxic and harmless properties. Among them, waterborne polyurethane coatings are widely used in the field of metal protection due to their excellent adhesion, chemical resistance and flexibility. However, the traditional waterborne polyurethane coating has poor antistatic performance and is difficult to meet the stringent requirements for static electricity protection in electronic equipment, oil pipelines, etc.

[0003] In order to improve the antistatic performance of waterborne anti-corrosion coatings, researchers usually introduce conductive fillers such as polyaniline and graphene oxide. Polyaniline is a typical conductive polymer with the characteristics of easy processing and adjustable conductivity. It can form a dense oxide film on the metal surface through passivation, thereby inhibiting corrosion. However, there is a strong π-π stacking interaction between polyaniline molecular chains, resulting in easy agglomeration in the coating, which affects the uniformity and mechanical properties of the coating. In addition, the hydrophobicity of polyaniline makes its dispersion in the waterborne system poor, further limiting its application.

[0004] As a two-dimensional nanomaterial, graphene oxide has excellent physical barrier properties and can extend the penetration path of corrosive media through the "labyrinth effect", thereby delaying metal corrosion. However, the surface of graphene oxide is rich in oxygen-containing functional groups (such as carboxyl, hydroxyl, etc.). Although these groups improve the hydrophilicity of graphene oxide, they also destroy its conductivity, resulting in extremely low conductivity. In addition, there is a strong π-π stacking interaction between graphene oxide layers, which is prone to agglomeration and reduces its dispersion stability in the coating.

[0005] In the prior art, researchers have attempted to improve the performance of fillers through physical mixing or simple modification, but the effects are limited. For example, CN103723716A uses a carbon coating process to improve the conductivity of graphene oxide, but this process is complex and costly, making it difficult to achieve large-scale industrial production. CN 112680076 A modifies graphene non-covalently, although it improves its dispersibility to a certain extent, the modification effect is easily affected by environmental factors and has poor stability. In addition, although the epoxy resin-based coating CN119463641A has excellent anti-corrosion performance, it is brittle and has poor flexibility, making it difficult to adapt to mechanical stresses under complex working conditions.

[0006] In recent years, researchers have begun to explore the use of multiple fillers in combination to synergistically improve the comprehensive performance of coatings. For example, CN119192959A discloses a preparation method of adding graphene oxide and polyaniline composites to anti-corrosion coatings, but it uses a physical mixing method, and the interfacial bonding force between the fillers is weak, which easily leads to the deterioration of the coating performance. CN 116948518A prepares a graphene oxide / polyaniline-epoxy resin composite coating by in-situ polymerization. Although it improves the anti-corrosion performance of the coating to a certain extent, it cannot fully utilize the electrochemical advantages of polyaniline, and the conductivity of the composite system is insufficient, so there are limitations in application scenarios requiring high conductivity and antistatic performance and cannot fully meet the needs of all scenarios. CN110591445A prepares an antistatic coating by blending silver nanowires with acrylic acid, and its surface resistance can be as low as 105Ω, but the silver nanowires are prone to change over time, and the relatively high cost (8wt% silver content) also limits large-scale application. CN118016452A blends PEDOT:PSS and silver nanowires and adds them to polyurethane. The results show that the addition of PEDOT:PSS not only significantly improves the dispersion of silver nanowires in the matrix but also acts as a bridge between silver nanowires. Therefore, the conductivity of the coating is greatly improved at a low silver nanowire content, but PEDOT:PSS is highly acidic (pH < 3), which will accelerate the corrosion of the metal matrix. CN112359437A introduces a preparation method of polyethylene / graphene composite fibers with excellent antistatic performance, but its reaction process is complex, requires high-temperature treatment, and does not solve the problem of improving the dispersion of the material in the coating.

[0007] Therefore, there is an urgent need to develop a highly dispersed and stable composite material to synergistically improve the conductivity network continuity, interfacial bonding strength, and anti-corrosion performance of coatings through chemical modification and structural design. For example, by regulating the structures of polyaniline and graphene oxide, not only can their dispersibility in aqueous systems be improved, but they also have excellent anti-corrosion and conductive properties, providing multiple protections and high performance for coatings. Summary of the Invention

[0008] To solve the problems described in the background art and the deficiencies of traditional waterborne polyurethane coatings in terms of anti-corrosion and antistatic properties, the present invention provides a polyaniline / modified graphene oxide composite material and a preparation method thereof in a waterborne polyurethane anti-corrosion and antistatic composite coating. First, graphene oxide is chemically modified using a modifier. The modifier molecule contains a flexible chain segment and an active amino group, which can effectively disrupt the strong π-π stacking interaction between graphene oxides, reduce the agglomeration tendency, and enable the modified graphene oxide to be uniformly dispersed in the aqueous system. It is particularly worth mentioning that the modification process significantly improves the dispersibility of graphene oxide and reduces the agglomeration phenomenon between particles, thus providing a uniform reaction interface for subsequent in-situ polymerization.

[0009] During the high-temperature curing process of waterborne polyurethane, the amino group in the modifier reacts with the abundant hydroxyl groups on the macromolecular chain of polyurethane to form a good interfacial bond, significantly enhancing the adhesion between the composite filler and the matrix and the overall mechanical properties. After modification, the interlayer spacing of graphene oxide increases (by 40%), releasing more active sites. This not only facilitates the in-situ polymerization of polyaniline but also enables polyaniline to coat the surface of graphene oxide in a uniform micro-nano state, thereby constructing a continuous and efficient conductive network. During this process, the dispersion performance of polyaniline is also greatly improved, ensuring its uniform distribution in the aqueous system, further enhancing the antistatic effect of the coating, and being able to quickly release static charge accumulation to make up for the deficiency of the poor antistatic performance of traditional waterborne polyurethane coatings.

[0010] In addition, graphene oxide itself has excellent physical barrier properties, and the diffusion path of corrosive media is extended through the "labyrinth effect"; while polyaniline can form a dense passivation layer on the metal surface to effectively prevent the spread of corrosion. Under the synergistic effect of the two, the coating not only forms multiple barriers to corrosive media but also further delays the corrosion process.

[0011] Finally, compared with the traditional physical mixing method, the use of chemical modification and in-situ polymerization processes can significantly enhance the interfacial bonding force between fillers, ensuring the uniform dispersion and long-term stability of the composite material in the coating. The entire preparation process is applicable to the aqueous system, avoiding the use of organic solvents and meeting the requirements of low VOC and environmental protection.

[0012] In summary, by combining the modification of graphene oxide and the in-situ polymerization of polyaniline, the present invention not only achieves remarkable results in improving the dispersibility and interfacial compatibility of graphene oxide and polyaniline but also constructs a continuous conductive network and forms a dual barrier for synergistic anti-corrosion, ultimately realizing the comprehensive performance optimization among anti-corrosion, antistatic, and mechanical flexibility, providing an environmentally friendly and excellent-performance solution for waterborne polyurethane anti-corrosion and antistatic coatings.

[0013] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0014] The present invention provides a preparation method of a polyaniline / modified graphene oxide composite material, comprising the following steps:

[0015] Step 1: Disperse graphene oxide into a beaker containing a dispersion liquid, and perform ultrasonic treatment to obtain a graphene oxide dispersion liquid;

[0016] Step 2: Place the graphene oxide dispersion liquid in a water bath pot, after complete water bath heating, add a modifier to perform modification treatment on the graphene oxide, and take it out and cool it after high-temperature treatment;

[0017] Step 3: Centrifuge the solution in Step 2, centrifuge it multiple times at room temperature, then remove the supernatant, freeze-dry the lower-layer precipitate, and grind it after complete freeze-drying to obtain modified graphene oxide powder;

[0018] Step 4: Disperse the modified graphene oxide powder in Step 3 into a beaker containing a doped acid solution, add a purified aniline solution, first perform ultrasonic treatment for 20 min, and then magnetically stir it in an ice-water bath at 0 - 4°C for 30 min to obtain an acid solution of modified graphene oxide / aniline; Dissolve ammonium persulfate in the doped acid solution and magnetically stir it in an ice-water bath at 0 - 4°C for 30 min to obtain an acid solution of ammonium persulfate;

[0019] Step 5: Under an ice-water bath at 0 - 4°C and magnetic stirring, slowly drip the acid solution of ammonium persulfate in Step 5 into the acid solution of modified graphene oxide / aniline in Step 4 with a dropper. After complete addition, wait for in-situ polymerization to be complete to obtain Product A;

[0020] Step 6: Perform suction filtration on the Product A obtained in Step 6, wash it repeatedly with ethanol and deionized water for several times until the filtrate becomes colorless, and dry the Product A in a vacuum oven at 60°C for 24 h to obtain a polyaniline / modified graphene oxide composite material.

[0021] Step 7: Add the polyaniline / modified graphene oxide composite material to deionized water and perform ultrasonic treatment for 20 min to obtain a polyaniline / modified graphene oxide dispersion liquid;

[0022] Step 8: Add the aqueous dispersion of the composite material in Step 7 to an aqueous polyurethane emulsion, so that the polyaniline / modified graphene oxide composite material accounts for a certain proportion of the total weight of the total solid content, and use a high-speed stirrer to obtain a uniformly dispersed polyaniline / modified graphene oxide-aqueous polyurethane composite coating;

[0023] Step 9: Prepare a coating by means of wire bar coating for the composite coating in Step 8, and cure it at 40°C for 12 h.

[0024] Further, in step 1, the dispersion used is phosphate buffer solution with a concentration of 0.01 mol / L and a pH of 5 - 7. Further, in step 2, the modifier is one or more of p-phenylenediamine, polyetheramine, m-phenylenediamine, and hexamethylenediamine, and the mass ratio of the modifier to graphene oxide is (1 - 50):1. Further, in step 4, the mass ratio of modified graphene oxide to aniline is (0.1 - 2):1.

[0025] Further, in step 4, the doping acid is one or more of dodecylbenzenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and styrenesulfonic acid, and the concentration of the doping acid is 0.8 - 1.2 mol / L.

[0026] Further, in step 8, the weight of the polyaniline / modified graphene oxide composite accounts for 0.1 wt.% - 5 wt.% of the total weight of the coating.

[0027] Further, in step 9, the thickness of the polyaniline / modified graphene oxide - waterborne polyurethane composite coating is 20 - 100 μm.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] Using a phosphate buffer solution with a concentration of 0.01 mol / L and a pH of 5–7 can fully disperse the graphene oxide (GO) sheets, prevent agglomeration, and promote the efficient amidation reaction between it and the modifier, thereby ensuring that the composite material has excellent electrical conductivity and mechanical strength. At the same time, the mass ratio of the modifier to GO directly affects the grafting position of amino groups on GO. This ratio not only determines the performance of the composite material in terms of electrical conductivity, corrosion resistance, and mechanical properties, but also ensures the subsequent in-situ polymerization to form a uniform conductive layer, improves the interfacial bonding force, prevents rapid reaction or particle agglomeration during the polymerization process, and ensures the stability of the overall performance of the material.

[0030] In addition, selecting an organic doping acid with good protonation function and surfactant characteristics can effectively activate the aniline polymerization reaction, while improving the interfacial compatibility between GO and aniline, promoting uniform dispersion and ordered polymerization. In contrast, although inorganic strong acids such as hydrochloric acid and sulfuric acid have stronger acidity, they are prone to cause over-oxidation and molecular chain breakage, and lack the interfacial regulation effect, which may ultimately affect the electrical conductivity, corrosion resistance, and long-term stability of the composite material. Therefore, the application of organic doping acid can not only achieve efficient polymerization, but also synergistically improve the various properties of the composite material.

[0031] In addition, the filler content and coating thickness are also important factors affecting the properties of the composite material. When the filler content is insufficient, it is difficult to form a continuous and effective conductive network, resulting in limited improvement in antistatic performance; while excessive fillers are prone to agglomeration, forming local concentration areas, which affect the coating flexibility and substrate adhesion, causing the conductive path to break or become discontinuous. At the same time, a thinner coating is prone to generate micropores or defects, reducing the anti-corrosion effect, while a thicker coating may crack, peel or wrinkle due to internal shrinkage stress during the curing process, which is not conducive to the overall protection performance.

[0032] By chemically modifying the carboxyl groups on the edges of graphene oxide, its dispersibility in waterborne polyurethane is significantly improved, avoiding coating defects (such as pores, cracks) caused by the agglomeration of traditional fillers. The adhesion reaches grade 0, and the pencil hardness is 5H, which is better than the traditional physical mixing method.

[0033] The in-situ polymerized polyaniline uniformly coats the surface of the modified graphene oxide in the form of nanofibers, and the conductivity is as high as 10.5 S·cm -1 , which is three orders of magnitude higher than that of pure GO (0.004 S·cm -1 ). The surface resistance is as low as 3.46×10 7 Ω, meeting the antistatic requirements, and significantly superior to single polyaniline or graphene oxide fillers.

[0034] Using macromolecular organic sulfonic acid as a doping acid can effectively activate the aniline polymerization reaction, and at the same time has surfactant properties, which helps to improve the interfacial compatibility between the modified graphene oxide and aniline, promoting uniform dispersion and ordered polymerization.

[0035] The combination of the physical barrier effect of the modified graphene oxide (layer spacing 1.06 nm, verified by XRD) and the passivation effect of polyaniline reduces the corrosion current density to 8.293×10 -9 A / cm 2 , which is three orders of magnitude higher than that of the traditional epoxy resin coating (corrosion current density ~10 -6 A / cm 2 ).

[0036] Through chemical modification, in-situ polymerization and structural design, the present invention solves the problems of poor conductivity of traditional coatings, easy agglomeration of fillers, and difficulty in coordinating anti-corrosion and antistatic properties. It has conductivity (10.5 S·cm-1), anti-corrosion property (corrosion current density 8.293×10 -9 A / cm 2 ), mechanical properties (adhesion grade 0) and environmental protection advantages, and is suitable for harsh environments such as pipelines and electronic devices. Brief Description of the Drawings

[0037] Figure 1Scanning electron microscope images of GO, AGO, and PANI / AGO prepared in Example 1 of the present invention

[0038] Figure 2 XRD patterns of GO and AGO prepared in Example 1 of the present invention

[0039] Figure 3 Surface resistance diagram of the PANI / AGO - waterborne polyurethane composite coating prepared in Example 1 of the present invention

[0040] Figure 4 Electrochemical polarization curve diagram of the PANI / AGO - waterborne polyurethane composite coating prepared in Example 1 of the present invention

[0041] Figure 5 Anticorrosion mechanism diagram of the waterborne polyurethane composite coating prepared in the present invention

[0042] Figure 6 Structure mechanism diagram of the polyaniline / modified graphene oxide composite material prepared in the present invention Detailed description of the specific implementation

[0043] The implementation of the present invention will be described in detail below with reference to the accompanying drawings. However, they do not constitute a limitation to the present invention and are only for illustration purposes. At the same time, through the description, the advantages of the present invention will be more clearly understood. All deformations that can be directly derived or associated by those of ordinary skill in the art from the content disclosed in the present invention shall be considered as within the protection scope of the present invention. The positional relationships described in the examples are consistent with those shown in the accompanying drawings, and other parts not detailed in the examples are prior arts.

[0044] Example 1

[0045] Step 1: Disperse 50 mg of graphene oxide into a beaker containing 50 mL of phosphate buffer solution (0.01 mol / L, pH = 5.5), and perform ultrasonic treatment to obtain a graphene oxide dispersion;

[0046] Step 2: Place the graphene oxide dispersion in a water bath, heat it to 90 °C, then add polyetheramine to modify the graphene oxide. The mass ratio of the modifier to graphene oxide is 20:1. After high - temperature treatment for 20 min, take it out and cool it;

[0047] Step 3: Centrifuge the solution in Step 2 multiple times at room temperature, then remove the supernatant, freeze - dry the lower - layer precipitate, and grind it after complete freeze - drying to obtain modified graphene oxide powder;

[0048] Step 4: Disperse 0.1 g of the purified aniline solution into a beaker containing 1 mol / L of 2-acrylamido-2-methylpropanesulfonic acid solution. Add modified graphene oxide powder (the mass ratio of modified graphene oxide to aniline is 1:1). First, ultrasonically treat for 20 min and then magnetically stir in an ice-water bath at 0 - 4 °C for 30 min to obtain an acidic solution of modified graphene oxide / aniline. Dissolve 2.28 g of ammonium persulfate in 1 mol / L of 2-acrylamido-2-methylpropanesulfonic acid solution, and magnetically stir in an ice-water bath at 0 - 4 °C for 30 min to obtain an acidic solution of ammonium persulfate.

[0049] Step 5: Under an ice-water bath at 0 - 4 °C and magnetic stirring, slowly drip the acidic solution of ammonium persulfate obtained in Step 4 into the acidic solution of modified graphene oxide / aniline obtained in Step 4 using a dropper. After complete addition, wait for in-situ polymerization to complete to obtain Product A.

[0050] Step 6: Filter the Product A obtained in Step 6 by suction filtration, and wash it repeatedly with ethanol and deionized water several times until the filtrate becomes colorless. Dry Product A in a vacuum oven at 60 °C for 24 h to obtain a polyaniline / modified graphene oxide composite material.

[0051] Step 7: Disperse the polyaniline / modified graphene oxide composite material into deionized water and ultrasonically treat for 20 min to obtain a polyaniline / modified graphene oxide dispersion.

[0052] Step 8: Slowly add the aqueous dispersion of the composite material in Step 7 to the aqueous polyurethane emulsion so that the composite material accounts for 1 wt.% of the total solid content of the coating. Use a high-speed stirrer to obtain a uniformly dispersed polyaniline / modified graphene oxide-aqueous polyurethane composite coating.

[0053] Step 9: Coat the composite coating in Step 8 on the surface of tinplate by means of wire bar coating, and cure at 40 °C for 12 h to make the thickness of the dry film 50 μm.

[0054] Example 2

[0055] In Step 2, adjust the ratio of the modifier to graphene oxide to 50:1.

[0056] In Step 4, adjust the mass ratio of modified graphene oxide to aniline to 2:1.

[0057] The remaining steps are the same as those in Experimental Example 1.

[0058] Example 3

[0059] In Step 1, adjust the pH value of the phosphate buffer solution to 7.

[0060] In Step 4, adjust the ratio of the modifier to graphene oxide to 10:1.

[0061] The remaining steps are the same as those in Experimental Example 1.

[0062] Example 4

[0063] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 20:1.

[0064] In Step 4, the doping acid is changed to 1 mol / L styrenesulfonic acid, and the mass ratio of modified graphene oxide to aniline is adjusted to 0.5:1.

[0065] The remaining steps are the same as those in Experimental Example 1.

[0066] Example 5

[0067] In Step 1, the pH value of the phosphate buffer solution is adjusted to 6.

[0068] In Step 4, the mass ratio of modified graphene oxide to aniline is 1:1.

[0069] The remaining steps are the same as those in Experimental Example 1.

[0070] Example 5

[0071] In Step 1, the pH value of the phosphate buffer solution is adjusted to 6.

[0072] In Step 4, the mass ratio of modified graphene oxide to aniline is 1:1.

[0073] In Step 9, the thickness of the coating is adjusted to 70 μm.

[0074] The remaining steps are the same as those in Experimental Example 1.

[0075] Example 6

[0076] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 20:1.

[0077] In Step 4, the doping acid is changed to 1 mol / L dodecylbenzenesulfonic acid, and the mass ratio of modified graphene oxide to aniline is adjusted to 1:1.

[0078] In Step 9, the thickness of the coating is adjusted to 20 μm.

[0079] The remaining steps are the same as those in Experimental Example 1.

[0080] Example 6

[0081] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 20:1.

[0082] In Step 4, the mass ratio of modified graphene oxide to aniline is 1:1.

[0083] In Step 9, the thickness of the coating is adjusted to 20 μm.

[0084] The remaining steps are the same as those in Experimental Example 1.

[0085] Example 7

[0086] In Step 1, the pH value of the phosphate buffer solution is adjusted to 6.5;

[0087] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 40:1;

[0088] In Step 4, the concentration of 2-acrylamido-2-methylpropanesulfonic acid is adjusted to 1.2 mol / L, and the mass ratio of modified graphene oxide to aniline is adjusted to 2:1;

[0089] The remaining steps are the same as those in Experimental Example 1

[0090] Example 8

[0091] In Step 1, the pH value of the phosphate buffer solution is adjusted to 5;

[0092] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 30:1;

[0093] In Step 9, the thickness of the coating is adjusted to 40 μm.

[0094] The remaining steps are the same as those in Experimental Example 1

[0095] Example 9

[0096] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 20:1;

[0097] In Step 4, the doping acid is adjusted to dodecylbenzenesulfonic acid at 1.2 mol / L;

[0098] In Step 9, the thickness of the coating is adjusted to 20 μm.

[0099] The remaining steps are the same as those in Experimental Example 1

[0100] Example 10

[0101] In Step 1, the pH value of the phosphate buffer solution is adjusted to 6.5;

[0102] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 30:1;

[0103] In Step 4, the concentration of 2-acrylamido-2-methylpropanesulfonic acid is adjusted to 1.2 mol / L.

[0104] The remaining steps are the same as those in Experimental Example 1

[0105] Example 11

[0106] In Step 2, the ratio of the modifier to graphene oxide is adjusted to 50:1;

[0107] In step 4, the mass ratio of the modified graphene oxide to aniline is 1:1.

[0108] In step 4, the doping acid is selected as 1 mol / L dodecylbenzenesulfonic acid.

[0109] In step 9, the thickness of the coating is adjusted to 40 μm.

[0110] The remaining steps are the same as those in Experimental Example 1.

[0111] Example 12

[0112] In step 1, the pH value of the phosphate buffer solution is adjusted to 6.5;

[0113] In step 2, the ratio of the modifier to graphene oxide is adjusted to 30:1;

[0114] In step 4, the doping acid is selected as 1.2 mol / L styrenesulfonic acid.

[0115] In step 9, the thickness of the coating is adjusted to 80 μm.

[0116] The remaining steps are the same as those in Experimental Example 1.

[0117] Test Example

[0118] Similar to Example 1, PANI / AGO with different addition amounts (2 wt%, 3 wt%, 4 wt%, 5 wt%) was mixed with waterborne polyurethane respectively, magnetically stirred for 30 min (1500 rpm), coated on the surface of tinplate with a wire bar, and cured at 40 °C for 12 h, and the coating thickness was 50 μm.

[0119] a. Scanning electron microscopy test

[0120] The surface morphology of the material was characterized by scanning electron microscopy. The filler was prepared into an aqueous dispersion with a mass concentration of 0.1 mg / mL, and a drop of the liquid was dropped on the optical surface of the silicon wafer, and the test sample was obtained after being placed in an oven at 60 °C for 6 h.

[0121] As Figure 1 shown in (a), serious agglomeration of polyaniline particles occurred, which may be caused by the strong interaction between PANI polymer chains. This agglomeration phenomenon indicates that in the absence of other modifiers or additives, PANI is prone to form larger particle aggregates, which may have an adverse impact on its electrical and mechanical properties. In Figure 1 (b), the surface of graphene oxide (GO) presents an obvious wrinkled morphology. This wrinkled structure is caused by the abundant oxygen-containing functional groups on the surface (such as carboxyl groups, epoxy groups, etc.), and these functional groups will cause the irregular surface morphology of GO. The wrinkled structure increases the specific surface area of GO, which may enhance its interaction with polymers (such as PANI) and improve the properties of the composite material.Figure 1 (c) shows polyetheramine-modified graphene oxide (AGO). After modification with polyetheramine, the surface structure and properties of GO have changed, and the surface wrinkles have significantly decreased. At Figure 1 (d), after PANI is combined with AGO, PANI particles mainly aggregate at the edges of AGO. This may be because a strong interaction is formed between polyaniline molecules and AGO during the combination process, resulting in PANI tending to aggregate at the edges of AGO. In addition, after modification with polyetheramine, the interlayer spacing of graphene oxide becomes larger, which may lead to more active sites appearing on the surface of graphene oxide, thus promoting the adsorption and aggregation of polyaniline.

[0122] c. X-ray diffraction test

[0123] It can be seen from Figure 2 that GO shows an obvious diffraction peak at 2θ = 11.74°, corresponding to the (001) crystal plane of GO. And AGO shows an obvious diffraction peak at 2θ = 8.38°. Compared with GO, the interlayer spacing of AGO has increased significantly, indicating that PEA has been successfully grafted onto GO. The increase in interlayer spacing weakens the π-π stacking effect between GO sheets, thus improving its dispersion in solvents and facilitating the formation of a uniform distribution in the composite material.

[0124] d. Electrochemical performance test

[0125] Figure 3 shows the surface resistivity of PANI / AGO composite coatings with different filler contents. As the content of conductive filler increases, the surface resistivity of the coating gradually decreases, and the filler gaps shrink to form an efficient conductive network, significantly improving the antistatic performance. Especially at 2 wt%, the surface resistance reaches 3.46×10 7 Ω, meeting the antistatic requirements (in the range of 106–109Ω). However, when the filler content exceeds the optimal addition amount, the improvement effect of conductivity tends to level off, and it may lead to a decrease in mechanical properties and local agglomeration phenomena. Figure 4 shows the polarization curve of the PANI / AGO composite coating. It can be seen that when the filler content is 2 wt% of the PANI / AGO coating, its corrosion potential is -0.446 mV, and the corrosion current density is 8.293×10 -9 A / cm 2 , showing excellent corrosion resistance. Therefore, 2 wt% filler is the optimal addition amount, with both good corrosion resistance and antistatic performance.

Claims

1. A method for preparing a polyaniline / modified graphene oxide composite material and a water-based anticorrosive and antistatic composite coating thereof, characterized in that Follow these steps: Step 1: dispersing graphene oxide into a beaker containing a dispersion liquid, and performing ultrasonic treatment to obtain a graphene oxide dispersion liquid; Step 2: placing the graphene oxide dispersion in a water bath, adding a modifier to modify the graphene oxide after the water bath is completely heated, and taking it out and cooling it after high-temperature treatment; Step 3: centrifuge the solution in step 2 for multiple times at room temperature, remove the supernatant, freeze-dry the lower precipitate, and grind it after freeze-drying to obtain modified graphene oxide powder; Step 4: Disperse the modified graphene oxide powder in step 3 into a beaker containing a doped acid solution, add the purified aniline solution, first ultrasonically treat for 20 minutes, and then magnetically stir in an ice water bath at 0-4°C for 30 minutes to obtain an acid solution of modified graphene oxide / aniline; dissolve ammonium persulfate in the doped acid solution and magnetically stir in an ice water bath at 0-4°C for 30 minutes to obtain an acid solution of ammonium persulfate; Step 5: In an ice water bath at 0-4°C and under magnetic stirring, slowly drip the acid solution of ammonium persulfate in step 5 into the acid solution of modified graphene oxide / aniline in step 4 using a rubber-tipped dropper, wait for the in-situ polymerization to be complete after the addition is complete, and obtain product A; Step 6: Filter the product A obtained in step 6, wash it repeatedly with ethanol and deionized water several times until the filtrate becomes colorless, and dry the product A in a vacuum oven at 60° C. for 24 h to obtain a polyaniline / modified graphene oxide composite material. Step 7: adding the polyaniline / modified graphene oxide composite material into deionized water and ultrasonically treating it for 20 minutes to obtain a polyaniline / modified graphene oxide dispersion; Step 8: adding the aqueous dispersion of the composite material in step 7 to the aqueous polyurethane emulsion so that the polyaniline / modified graphene oxide composite material accounts for a certain proportion of the total solid content by weight, and using a high-speed stirrer to obtain a uniformly dispersed polyaniline / modified graphene oxide-aqueous polyurethane composite coating; Step 9: Prepare a coating by wire rod coating the composite coating in step 8 and cure it at 40° C. for 12 h.

2. The method for preparing the polyaniline / modified graphene oxide composite material according to claim 1, characterized in that: In step 1, the dispersion liquid is a phosphate buffer with a concentration of 0.01 mol / L and a pH of 5-7.

3. The method for preparing the polyaniline / modified graphene oxide composite material according to claim 1, characterized in that: In step 2, the modifier is one or more of p-phenylenediamine, polyetheramine, m-phenylenediamine and hexamethylenediamine, and the mass ratio of the modifier to graphene oxide is (1-50):

1.

4. The method for preparing the polyaniline / modified graphene oxide composite material according to claim 1, characterized in that: In step 4, the mass ratio of modified graphene oxide to aniline is (0.1-2):

1.

5. The method for preparing the polyaniline / modified graphene oxide composite material according to claim 1, characterized in that: In step 4, the doping acid is one or more of dodecylbenzenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and styrenesulfonic acid, and the concentration of the doping acid is 0.8-1.2 mol / L.

6. The method for preparing the polyaniline / modified graphene oxide-aqueous polyurethane composite coating according to claim 1, characterized in that: In step 8, the weight of the polyaniline / modified graphene oxide composite material accounts for 0.1wt.%-5wt.% of the total weight of the coating.

7. The method for preparing the polyaniline / modified graphene oxide-aqueous polyurethane composite coating according to claim 1, characterized in that: In step 9, the thickness of the polyaniline / modified graphene oxide-aqueous polyurethane composite coating is 20-100 μm.

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